Conventionally, a laser or synchrotron radiation light (called "SR light" hereunder) is known as a light beam. The laser has a wavelength of the visible light region and its neighboring region. On the other hand, the SR light has a wavelength ranging from infrared rays to an X-ray of a long wavelength.
In the meantime, with the present technique for light beam generation, the generation of light is restricted to the X-ray region of a long wavelength, like in the SR light. In other words, it is impossible to generate an X-ray of a short wavelength and a monochromatic light beam, namely, a monochromatic gamma ray beam, which has photon energy of, for example, 0.1 MeV or more far higher than the X-ray of a short wavelength.
An object of the present invention is, therefore, to provide a generating method and apparatus for generating high energy light beams, namely, a short wavelength X-ray beam and a monochromatic gamma ray beam, which are excellent in the degree of monochrome and which have low noise.